A man smoking and selling Tobacco at an Auction floor. Image credit voanews.com ZIMSEC O Level Combined Science Notes: Substance Abuse: Smoking
Image credit citifmonline.com ZIMSEC O Level Combined Science Notes:Contraception: The pill
How it works
Sewage treatment works at Morton Jaffray,Harare. Image credit hararenews.co.zw ZIMSEC O Level Combined Science Notes: Centralised Sewage Treatment Works
ZIMSEC O Level Combined Science: Carbon Dioxide and Photosynthesis
Aim: To test whether carbon dioxide is necessary for photosynthesis.
Materials: Potted green plants, potassium hydroxide solution (soda lime), two polythene bags/two bell jars, string, apparatus and reagents for the start test.
Image credit schule-bw.de ZIMSEC O Level Combined Science Notes: Amylase enzyme experiment
Experiment
Materilas: 1% amylase enzyme/saliva, 2% startch solution, visking tubing, reagents to test for starch and sugar, beakers.
Method A: Visking Tubing.
Coloured ink droplets falling and diffusing in a glass of water. Image credit pinterest.com ZIMSEC O Level Combined Science Notes:The movement of molecules
The basic structure of a flower: showing the reproductive organs ZIMSEC O Level Combined Science Notes: Reproduction in plants: Flowers and Pollination
Leach the soil ZIMSEC O Level Combined Science Notes: Comparing leaching in soils
Materials: soil samples, distilled water, burners, 3 beakers, measuring cylinders, cotton wool, filter funnel
Method 
Boil the filtrate
Elements arranged according to their proton number. Image credit wallpapercave.com ZIMSEC O Level Combined Science Notes: Elements and the proton number
The cross section of beams ZIMSEC O Level Combined Science Notes: Strength to Mass ratio
